Hi, it was published in The Drapier's Letters (1724-1725). This was a series of 7 pamphlets written by Jonathan Swift under the guise of the ‘Drapier’, a Dublin shopkeeper, in order to protest at England's treatment of Ireland as a ‘depending Kingdom’. This famous controversy began with an economic and legal dispute over the grant of a patent to William Wood, an English entrepreneur, to mint halfpence for Ireland. During 1724 Swift published five pamphlets on the issue: A Letter to the Shopkeepers, A Letter to Mr Harding, Some Observations upon a Report, A Letter to the Whole People of Ireland, and A Letter to Lord Viscount Molesworth. A sixth pamphlet, A Letter to the Lord Chancellor Middleton, was written in that year, but withheld for legal reasons. In 1725 a final pamphlet, An Humble Address to both Houses of Parliament, was shelved when the Government withdrew Wood's patent. Source: www.answers.com

A better question is where was the letter mailed to? :P